If white only has a K + B, I think the key word here is "forced". If white has a forced win, even with just a king and bishop, then black should be able to lose on time (not draw on time). If there is no forced win, black should draw if he "loses" on time.

What everyone forgets is that there is no one set of chess rules. FIDE have their rules, the USCF have their rules, and Chess.com have their rules . Each set of rules is slightly different (I imagine that other organizations also have rules that differ slightly from each other) . You have to know whose rules apply to the game that you are playing.

If white only has a K + B, I think the key word here is "forced". If white has a forced win, even with just a king and bishop, then black should be able to lose on time (not draw on time). If there is no forced win, black should draw if he "loses" on time.

What if the weaker side (losing on the board/winning on time) has more than just 2 pieces (including the king)? For instance, if he's down by a queen in the midgame? I would suppose that the stronger side would have a forced win, but it can't really be proven. And what about borderline situations where Houdini can find a forced win, but the human player with the stronger position most likely can't?

If white only has a K + B, I think the key word here is "forced". If white has a forced win, even with just a king and bishop, then black should be able to lose on time (not draw on time). If there is no forced win, black should draw if he "loses" on time.

What if the weaker side (losing on the board/winning on time) has more than just 2 pieces (including the king)? For instance, if he's down by a queen in the midgame? I would suppose that the stronger side would have a forced win, but it can't really be proven. And what about borderline situations where Houdini can find a forced win, but the human player with the stronger position most likely can't?

The side that is down material and winning on time should be able to claim a win on time provided that (A) he has mating material, or (B) he doesn't have mating material but can find a forced win.

So it doesn't matter how much material a player is down; as long as he is able to mate, he can claim a win on time. If not, then when his opponent flags, it's a draw.

It doesn't matter if the stronger side (materialistically) has a forced win if he flags. He will still lose on time if his opponent has mating material, or draw if he doesn't.

If white only has a K + B, I think the key word here is "forced". If white has a forced win, even with just a king and bishop, then black should be able to lose on time (not draw on time). If there is no forced win, black should draw if he "loses" on time.

What if the weaker side (losing on the board/winning on time) has more than just 2 pieces (including the king)? For instance, if he's down by a queen in the midgame? I would suppose that the stronger side would have a forced win, but it can't really be proven. And what about borderline situations where Houdini can find a forced win, but the human player with the stronger position most likely can't?

The side that is down material and winning on time should be able to claim a win on time provided that (A) he has mating material, or (B) he doesn't have mating material but can find a forced win.

So it doesn't matter how much material a player is down; as long as he is able to mate, he can claim a win on time. If not, then when his opponent flags, it's a draw.

It doesn't matter if the stronger side (materialistically) has a forced win if he flags. He will still lose on time if his opponent has mating material, or draw if he doesn't.

Oh, I see what you mean now. That makes sense. So that's how it works on chess.com?

That's how it should work anyway on chess.com. In OTB chess there's a TD to make sound decisions, which is difficult to do when you're online. For example, determining whether there is a forced win in the position should be done by a TD.